Optical signaling apparatus

ABSTRACT

409,073. Photophones. ZEISS, C., [Firm of], Carl-Zeiss-Strasse, Jena, Germany. Dec. 17, 1932, No. 35814. Convention date, Dec. 23, 1931. [Class 40 (v).] Some parts of an optical signalling apparatus are used for both transmission and reception, and the necessary changes in the other electric and optical parts are made by a single switch k, Fig. 1. For transmission an electromagnet f&lt;1&gt;, traversed by the signals, moves a prism d to and from a reflecting-surface c&lt;1&gt; and thus modulates the reflection of light incident from a source g. For reception a constant current is passed through the electromagnet of such strength the prism is pressed tightly against the reflecting surface so that the received incident light passes uninterruptedly to the selenium cell h. According to a modification, Fig. 2, the light from a source r is modulated by a movable diaphragm p. The side opposite the source has an inclined surface v which, in the position where the light from the source r is completely cut off, deflects the received light to a light-sensitive cell u.

FIPSlOb AU 233 EX Sept. 11, 1934. R. MECHAU I OP GAL SIGNALING APPARATUS Filed D90. 16. 1932 Examiner In vemon:

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Patented Sept. 11, 1934 UNITED STATES Examiner PATENT OFFICE OPTICAL SIGNALING APPARATUS Robert Mechau, Jena, Germany, assignor to the firm of Carl Zeiss, Jena, Germany Application December 16, 1932, Serial No. 647,625 In Germany December 23, 1931 2 Claims.

Similarly to flash apparatus, optical signaling devices are conveniently so constructed as to combine a transmitter and a receiver in one self-contained apparatus. This construction is simple and cheap, since certain parts of the transmitter and the receiver, for instance the objectives or the reflectors converging the received or transmitted rays, may be replaced by single parts that can be used in either component apparatus. Nevertheless, it is not possible to avoid changing other parts, for instance the light source of the transmitter and the light-sensitive cell of the receiver or the microphone and the telescope, these changes being efiected according to whether the apparatus is to be used as a transmitter or as a receiver. When apparatus for phototelephony are concerned, which require specially frequent changes, the above mentioned construction may entail a considerable disadvantage in so far as in this case, in which, frequently, use is to be made of complicated electric amplifying devices, not only optical but also many electric parts require being changed. The invention proves, however, that it is comparatively simple to electrically control by means of one single switch not only all electrical parts to be changed but also the respective optical parts.

An especially simple apparatus is arrived at in the latter case when that part to which the variable current, for instance the microphone current, is supplied in order to produce the lightpencil modulations required in transmitting, may be used also for moving the displaceable optical parts into the positions which these parts are to assume when the apparatus is used as a receiver.

In the case of, for instance, a telephonic apparatus, in which, when used for transmission, the pencil of light rays is modulated by means of a body which, through the agency of an electromagnetic device, is brought more or less near a totally reflecting surface struck by the pencil of rays so that. according to the sound modulations. it reflects, or is traversed, by a greater or smaller quantity of the light, it is convenient to change the apparatus to reception by supplying to the said electro-magnetic device such a quantity of current of unvariable strength that, according to the manner in which the apparatus is working, the said body is pressed tightly against, or completely raised from, the reflecting surface, so that the ray pencil which is to be received, and which strikes the reflecting surface, leaves this surface in as strong a condition as possible, either by completely traversing this surface or by being reflected thereon as completely as possible.

In the case of an apparatus in which the light pencil to be emitted is modulated by means of a diaphragm displaceable in its plane, fixed for instance to the movable conductor of a string galvanometer, that side of the diaphragm which does not face the light source of the emitter is conveniently provided with an inclined reflecting surface which, when the diaphragm is given that position in which it stops down completely the emission light pencil, deviates the reception light pencil to one side in such a manner that this light may be received by a light-sensitive cell or the like. Also in this case, that part of the apparatus which effects the light modulations in the transmission may be used for changing the respective optical part to reception position.

Figure 1 of the accompanying drawing represents by way of example an apparatus according to the invention in a longitudinal section, in which the variation of the reflexion of a totally reflecting surface produces the light modulations in transmission. Figure 2 shows part of this apparatus in side elevation and on an enlarged scale. Figures 3 and 4 represent schematically the optical parts of an apparatus in which the modulations are effected by an oscillating diaphragm, Figure 3 illustrating this apparatus in reception condition, and Figure 4, in transmission condition. Figure 5 shows part of this other apparatus in side elevation.

In the apparatus represented by Figure 1, a housing it contains an objective b. In the focus of this objective is disposed a surface 0 of a rhomboidal prism c, this surface being bounded by air. A small prism d is disposed behind the surface c at the spot at which the optical axis traverses this surface. The prism d is held by a pin e displaceable in its longitudinal direction and fixed to a polarized diaphragm e. The polarized diaphragm e represents the armature of a permanent magnet I having a coil f When no current flows in the coil I the magnet 1 provides a medium tension in the diaphragm e, and the prism d is at a medium distance from the surface 0 By supplying a strong current to the coil i the prism (1 may be tightly pressed against the surface c In the housing a is disposed also a selenium cell it and a glow lamp g which emits visible light rays. The lamp may also be so constructed, for instance, that it emits ultra-red light rays. Between the glow lamp g and the prism c is disposed a condenser g which projects on the surface 0 an image of the incandescent filament of the lamp 9. Between the prism c and the selenium cell h is provided a converging lens h which images on the cell h the axial point lying on the surface c Finally, there is provided behind the glow lamp 9, outside the housing a, a magnifier i which is focused to the incandescent filament of the lamp 9. By means of this magnifier, the apparatus is adjusted.

The source of current is a battery By means of a bi-pble throw-over switch is this battery may be connected to the primary circuit of a transformer Z in which is-disposed a microphone m. The secondary coil of this transformer is connected to the magnet coil f By throwing over the switch It, the battery j-may be connected to the coil f also direct, the arrangement being such that in this case also the selenium cell It is connected in series to the battery 7' and a telephone n.

The apparatus Works in the following manner.

When the apparatus is to be used as a transter, the throw-over switch k is given the posit1 n represented in the drawing by full lines. A continuous current now flows from the battery 7 ti ugh the microphone m and the primary coil he transformer Z. The magnet f is not yet excited, and the diaphragm e remains in its medium position. When the microphone m is spoken at, a modulated current arises in the secondary circuit of the transformer Zand the diaphragm e and the prism 01 oscillate according to the rhythm of the spoken words about their medium position. In the same rhythm, the ray pencil emitted by the light source g to the surface 0 is reflected more strongly or weakly thanbefore, and the ray pencil emanating from the apparatus is modulated accordingly.

When th apparatus is to be used as a receiver, it is s ufii?nt.to give the throw-over switch is the positi n represented in the drawing by dash lines, A comparatively strong current flows from the battery 7' tiandthroughthe magnet coil f and, as a conse r ce; the diaphragm is repelled and the prism d essed tightly against the surface e. The ray manating from the light source. g traverse the urface 0 completely and are absorbed behind this surface. Rays received by the exterior side of the objective I) also traverse the surface c unobstructedly and arrive at the selenium cell 71.. As soon as the switch is assumes the position represented by dash lines, a continuous current flows through the cell it and the telephone n. When the received ray pencil is modulated, the modulations are heard in the telephone.

The apparatus according to Figures 2 and 3 contains an objective 0, a diaphragm p (which is hatched in the drawing), a condenser q, and a light source T. To the diaphragm p is connected a small rectangular isosceles prism s the hypothenuse surface of which is silvered. At one side of the prism is disposed a converging lens t, and behind this lens, a selenium cell u. The diaphragm p is fixed to the displaceable conductor 2) of a string galvanometer, and the conductor '0 oscillates transversely to the optical axis A-A in the field of a permanent magnet w.

It is obvious that, by directing the electric current accordingly, the apparatus may be used as a receiver or transmitter. When the apparatus is to be used as a receiver, a constant current is supplied to the string '0, so that the diaphragm 1: assumes the position represented in Figure 2.

When a pencil of visible or invisible parallel rays now arrives at the objective 0, this objective concentrates the said pencil to the hypothenuse surface of the prism s, whence the rays are deviated to the converging lens t and arrive at the selenium cell it in which, as in the apparatus according to Figure 1, modulations of the pencil of light are transformed to fluctuations of current. In this case, the light of the lamp r is stopped down by the diaphragm 10. When the apparatus is to be used as a transmitter, only so much current flows through the string 0 that the diaphragm p assumes the medium position represented in Figure 3. Half of the ray pencil emitted by the emitting light source 1', which is converged by the lens q, passes the diaphragm 1), its rays being made parallel by the objective 0. When the current in the string is varied by speaking against a microphone connected to the circuit of the string or, for instance, by making a buzzer influence this microphone, the string oscillates and produces a corresponding modulation of the emitted ray pencil.

I claim:

1. A signaling apparatus, containing, a light source for emitting signals, an element sensitive to rays, this element being adapted to receive signals, optical and electric parts only for emitting signals, optical and electric parts only for receiving signals, optical and electric parts for emitting as well as for receiving signals, the optical parts being adapted only to transmit comprising a diaphragm which, when in operative position, is movable in the path of the rays of the ray source, and the optical parts which are only adapted for receiving having a transverse refiecting surface rigidly connected to that side of the diaphragm which does not face the ray source, this transverse surface being adapted, when in operative position, to direct the rays entering the apparatus to the said ray sensitive element, the apparatus further comprising a switch connected to the optical parts and electrically connected to the electric parts, this switch being adapted to bring into operative position the optical and electric parts when changing from transmission to reception and vice versa.

2. A signaling apparatus for emitting and receiving signals, comprising a housing, a light source disposed in the housing, a prism also disposed in the housing and having a totally reflecting surface, a condenser provided between the source of rays and the prism, this condenser being adapted to converge the rays on the said surface, an objective provided in the housing and adapted to direct towards outside the rays emanating from the said surface, another prism movably mounted in the housing and adapted to vary its distance from the said surface, an electro-magnet adapted to act on this other prism, and a microphone electrical connected to the said electro-magnet, a cell sensitive to rays disposed in the housing, a co. verging lens provided between the said other 1:: ism and the cell, this converging lens being adapted to converge on the cell rays traversing this prism, a telephone electrically connected, for the purpose set forth, to the cell, a battery and a throwover switch electrically connected to the microphone, the telephone, the cell and the electromagnet.

ROBERT MECHAU. 

